At present, power distribution substations are made as monolithic structures, taking the form of containers or buildings. Such concept brings about a number of inconveniences, mainly due to quite large external dimensions of the finished facilities and limited possibilities of prefabrication. The modular substation enclosure which is the subject of this patent application allows to shorten the time of design and construction, and thereby to reduce the costs. In addition, the small dimensions of individual components make their galvanic corrosion protection possible, and the unique concept of the external plating combined with the applied technical solutions considerably reduce the number of heat bridges, which results in good thermal insulation.